1. Field of the Invention
The present invention relates to a wireless communication system. More particularly, the present invention relates to methods for determining parameters for an idle mode in a wireless communication system, and Base Station (BS)/Mobile Station (MS) apparatuses and operation methods for paging in an idle mode in a wireless communication system.
2. Description of the Related Art
Research is being conducted to provide various services with a data rate of about 100 Mbps in an advanced 4th Generation (4G) communication system. The 4G communication system is evolving to support mobility, high data rates, and a high Quality of Service (QoS) in Broadband Wireless Access (BWA) systems such as a Local Area Network (LAN) system and a Metropolitan Area Network (MAN) system. Typical examples of the above system employ the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standards.
According to the IEEE 802.16 standards, if there is no Transmit/Receive (TX/RX) traffic for a certain amount of time, a Mobile Station (MS) operates in an idle mode to minimize power consumption. That is, if there is no TX/RX traffic for a certain amount of time, the MS transmits a DeREGistration REQuest (DREG-REQ) message to a serving Base Station (BS) in order to operate in an idle mode. Upon receiving the DREG-REQ message, the serving BS transmits a DeREGistration CoMmanD (DREG-CMD) message to the MS in order to allow the MS to transition to an idle mode. A description of the details of the DREG-REQ/CMD messages, which are not directly related to the present invention, will be omitted for conciseness.
The DREG-CMD message includes a paging information Type/Length/Value (TLV) field. The paging information TLV field includes a paging group identifier, a paging cycle parameter, and a paging offset parameter.
The paging group identifier is used to identify a paging group including a plurality of cells. The paging cycle parameter is determined according to a paging cycle request made by the MS. The paging offset parameter is used to determine the time to page the specific MS by using a frame number and the paging cycle parameter.
An idle-mode operation process is defined in the IEEE 802.16e standard. The idle-mode operation process defined in the IEEE 802.16e standard is also applicable to a system employing the IEEE 802.16m standard, which is an evolved version of the IEEE 802.16e standard. Hereafter, systems employing the IEEE 802.16e standard and the IEEE 802.16m standard will be referred to as an IEEE 802.16e system and IEEE 802.16m system, respectively. However, unlike the IEEE 802.16e system performing a frame-based operation, the IEEE 802.16m system performs a superframe (including several frames)-based operation and transmits system Broadcast CHannel (BCH) information on a superframe basis. Thus, the IEEE 802.16m system requires an idle-mode operation based on the superframe.
In addition, because paging group identifier information is included in a paging advertisement message (i.e. a MOB_PAG-ADV message) of the IEEE 802.16e system, even if there is no target to page and no need to transmit the MOB_PAG-ADV message in a paging listening interval, the IEEE 802.16e system always transmits the MOB_PAG-ADV message in the paging listening interval in order to notify the paging group identifier information to the corresponding MSs. Because the MOB_PAG-ADV message is robustly encoded prior to transmission, the transmission of the MOB_PAG-ADV message for notification of the paging group identifier may cause an overhead. Thus, the paging group identifier information needs to be separated from the MOB_PAG-ADV message.